Human Health and Environmental Risks

Citizen Scientists Margie Richard started a grassroots effort to clean up the air in Norco, Louisiana. Confronted the Shell Oil Company. Gathered data about what toxins were being diffused into the atmosphere. Determined that Shell was releasing .9 million kg of toxic chemicals into the air each year. Won the battle with Shell buying up the homes, cleaning up their emissions, and paying the state and community for their polluting.

Human Health Risk Factors (1) Physical Natural disasters, UV exposure, radiation (2) Biological Infectious diseases (3) Chemical Arsenic, PCB’s, synthetic chemicals & pesticides

Infectious Diseases: caused by pathogens. Non-infectious Diseases: cancer, cardiovascular diseases, respiratory, and digestive diseases. Pathogens (vectors): Viruses Bacteria Fungi Protists

SIX Illnesses account for 94% of all infectious-disease-related Deaths Respiratory infections (pneumonia) Auto Immune Deficiency Syndrome (AIDS) Diarrhea Tuberculosis Malaria Childhood diseases (measles/tetanus) Acute vs. chronic diseases?

Chronic Risk Factors Low Income High-Income poverty Tobacco use Unsafe drinking water (diarrhea) Less active lifestyle Poor sanitation overnutrition Malnutrition (pneumonia) High blood pressure MANY YOUNG die obesity

Infectious Diseases Have Killed Large Numbers of People Epidemic: when a pathogen causes a rapid increase in disease. Pandemic: when an epidemic occurs over a large geographic region such as a continent.

Plague (Bubonic plague/Black Death): bacteria carried by fleas. Swollen glands, black spots, and extreme pain. Estimated to have killed hundreds of millions of people. Nearly ¼ of the European population in the 1300s.

Malaria Infection caused by an infection from one of the several species of the protist Plasmodium. One stage of the life cycle in the human, the other in the mosquito. Causes recurrent flulike symptoms. Sub-Sahara Africa, Asia, the Middle East, and Central and South America are hit the hardest.

Tuberculosis: highly contagious disease caused by a bacterium that infects the lungs. Spread when a person coughs and expels the bacteria into the air. Weakness, night sweats, and coughing up blood. Can be infected but not develop the disease. 9 million develop the disease and 2 million die. Treated with antibiotics.

Emergent Infectious Diseases Infectious diseases that were previously not described or have not been common for at least the prior 20 years. Many can pass from animals to humans. Particular concern because of the rapid movement of people and cargo.

HIV/AIDS Human Immunodeficiency Virus (HIV) spread through sexual contact and by sharing drug needles. Found in the African nation of Cameroon. Local hunters were butchering and eating the chimp meat. 33 million infected, 25 million have died. New antiviral drugs have been able to maintain low HIV populations inside of the human body.

Ebola Hemorrhagic Fever Discovered in the Democratic Republic of Congo near the Ebola River. Kills a lot of people that are infected. Fever, vomiting, internal and external bleeding. Natural source has not been found. Recent breakout in 2014.

Mad Cow Disease Neurological disease that damages a cow’s nervous tissue. Loose coordination of its body then dies. Prions: proteins that mutates into deadly proteins that act as pathogens. Transmission requires an uninfected cow to consume the nervous tissue of an infected cow.

Bird Flu Caused by the H1N1 virus. In 2006 the virus mutated and turned into H5N1. People in close contact with birds contracted it. Not easily passed between people.

West Nile Virus Lives in bird species, transmitted among birds by mosquitos. Causes brain swelling leading to illness, sometimes death. Appeared in the US in 1999. Quickly spread through the US. Kept under control by mosquito control.

Toxicology is the Study of Chemical Risks Humans have developed many different chemicals. Some are very helpful while others are often by-products from industry.

Determining Health Effects of Pollutants Toxicology Acute toxicity -v- Chronic toxicity Symptoms often mimic other diseases- hard to assess source

Types of Chemicals Neurotoxins Disrupt nervous system Effect Example Neurotoxins Disrupt nervous system Insecticides, Lead, Mercury Carcinogens Create cancers Asbestos, radon, formaldehyde, tobacco, cadmium, PCB’s Teratogens Interfere with embryo/fetus development Thalidomide, alcohol Allergens Allergic reactions Peanuts, milk, whey, penicillin Endocrine Disruptors Interfere with hormones DDT, atrazine, Phthalates

Endocrine Disruptors Animal hormone injections Human birth control pesticides feminization

Dose Response Studies Expose animals or plants to different amounts of a chemical and them observe a variety of responses. LD50: the lethal dose that kills 50% of the group. Can be used to compare the value to thousands of previous tests.

How Much of a Chemical Will Harm Me?

ED50: the effective dose that causes 50% of individuals to display harmful but non-lethal effect. Ex: carcinogen, neurotoxin, behavior changes.

Testing Standards Toxic Substances Control Act of 1970: EPA has the authority to regulate many chemicals excluding food, cosmetics, and pesticides. Federal Insecticide, Fungicide and Rodenticide Act 1996: A pesticide will not generally cause unreasonable adverse effects on the enviornment.

Humans: Use rats and mice to determine the LD50 or ED50 Humans: Use rats and mice to determine the LD50 or ED50. Then that value is divided by 1000 to set safe values for humans.

artificial sweeteners debate

Aspartame Aspartame Rat Experiment Prooves Dangers

Problems of Determining Carcinogens Rats: short term exposure to high levels Humans long term expose to low levels Can we compare two different species Same effects in both organisms?

Children and Chemical Exposure Children more susceptible to chemicals Weigh less than adults Bodies are still developing Play on floors and lawns Exposed to cleaning products and pesticides Put things into their mouths

Retrospective Studies: monitor people who have been exposed to a chemical at some time in the past. Prospective Studies: monitor people who might become exposed to harmful chemicals. Synergistic Interactions: two risks together cause more harm than one would expect. Example: effects of asbestos can be higher if an individual also smokes tobacco.

Retrospective Studies Case Study: Bhopal India Pesticide plant released 36,000 kg of gas

Retrospective Studies Case Study: Chernobyl Nuclear Accident

Factors determining Concentrations in Organisms (1) Route of Exposure

(2) Solubility, Bioaccumulation, Biomagnification Water-v-fat soluble Oil soluble chemicals stored in fatty tissues Ex: mercury, DDT, PCB’s DDT in birds that eat fish is 8 million times that found in water

(3) Persistence

Risk Analysis: Assess, Accept and Manage Risk Environmental Hazard: anything in our environment that potentially causes harm. Examples: smoking, volcanoes, draining swamps, air pollution.

Does not always match reality. Quantitative: Risk Assessment Qualitative: Decisions based on perceptions (how we feel about it..no data involved). Does not always match reality. Quantitative: Risk=s probability of being exposed to a hazard x probability of being harmed if exposed.

Risk Acceptance The level of risk that can be tolerated. Difficult part of management. No amount of information on the extent of the risk will overcome the conflict between those who are willing to live with some amount of risk and those who are not!

Risk Management Integrates the scientific data in addition to the analysis of acceptable levels of risk with economic, social, ethical, and political issues. Worldwide Standards of Risk Innocent-until-proven-guilty principle. Precautionary Principle: when a hazard is plausible but not yet certain, get rid of it!

Stockholm Convention 12 banned “Dirty Dozen”. All were known to be endocrine disruptors.